I.C. Engine Testing

Practical Training Report submitted by Sonia Deva and Preeti Bains

under guidance of

Prof. S.K. Sane and Kailash Kotwani

Center for Aerospace System and Design Engineering Department of Aerospace Engineering

Indian Institute of Technology, Bombay July 2004

Contents

Contents Preface Nomenclature

1. Introduction 2. Theory 3. I.C. Engines Experiments

3.1 Effect of Exhaust Diverter on Thrust 3.2 Drag of Set Up

3.3 Ct vs J Comparison of I.C. Engine and D.C. electric Motor 3.4 SFC / TSFC

References Acknowledgements

Preface We had undergone one month of summer training under the apt guidance of Prof. S.K. Sane. Most of the time we assisted him in writing book on Thermodynamics. We, a team of four members, together worked on making useful Thermodynamics Tutor for B.E. first year student. For this we looked for many examples in various books, searched net. We tried our level best to introduce latest concepts, new examples to incorporate in the tutor.

In addition to that we conducted some of experiments for characterization of a propeller on I.C Engine. Another problem was Determining SFC/TSFC data of particular combination of engine, propeller and fuel.

We spend some time in learning Programming and tools like MATLAB and X-Foil. We were assigned the task of writing a code which will determine moment coefficient of MAV. We will continue this work at our place. -Sonia -Preeti

Nomenclature

MAV - Mini Aerial Vehicle CT - Coefficient of thrust CP - Coefficient of power RPM - Revolutions per minute n - Revolutions per second D - Diameter of Propeller in inches J - Advance Ratio I.C. - Internal Combustion S.F.C. - Specific Fuel Consumption T.S.F.C. - Thrust Specific Fuel Consumption T - Thrust r - Density of air

V - Free stream velocity P - Power t - Time in sec

1. Introduction

The main goal behind carrying out the Power plant experiments is to have a right combination of propeller and engine/motor so as to have minimum weight of propulsion system with maximum efficiency. For the same various propeller-engine combinations are tested in wind tunnel at different flow velocities and RPM. We measure the various parameters like Thrust, SFC, TSFC, and Drag of set-up etc. Various instruments used in testing were Load Cell (Thrust), Pitot Static tube and Micro-manometer (Tunnel Velocity), RPM sensor (Propeller RPM) and Weighing balance (Fuel Weight). In the present study 11 x 7 propeller with OS Max 0.46 LA engine and Methanol fuel (+ 5% Nitromethane + 20 % Castor Oil) were tested in wind tunnel.

Image 1: I.C. Engine Set-up

2.Theory

The various parameters measured in the experiment are CT , J, SFC, TSFC. CT is the coefficient of the thrust given by

CT= 42DnT

r (1)

Where T is the thrust of the propeller. It is measured using Load cell clamped below engine mount and the reading is taken from its indicator outside tunnel. J, advance ratio, which is a measure of how far a propeller, moves forward through the medium per rotation of the propeller given by

J =nDV (2)

Similarly, Power Coefficient is defined as

CP= 53DnP

r (3)

SFC, Specific Fuel Consumption, is the amount of fuel consumed to produce unit power in unit time. It is given by

SFC=tP

W

(4)

Where W = Weight of the fuel consumed in time t.

TSFC, Thrust Specific Fuel consumption, is given by

TSFC =t.T

W (5)

3. I.C. Engine Testing 3.1 Effect of Exhaust Diverter on Thrust: The experiment for thrust measurement with and without using the exhaust diverter were performed. The results of the two were compared.

load Vs rpm for 11X7 propeller

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 2000 4000 6000 8000 10000 12000

RPM

LOA

D (

kg)

load vs rpm (without exhaust ) load Vs rpm (with exhaust) Graph 1: Load Vs Rpm for 11x7 Propeller. It was observed the effect of attaching the exhaust diverter to the muffler was negligible. The two curves overlap. Hence, an exhaust diverter on muffler is not producing any considerate effect on the thrust values. 3.2 Drag of setup Some of the thrust produced by the propeller is wasted in overcoming the drag of the setup. So, the thrust reading what the load cell gives for the propeller is not the actual thrust produced by the propeller. In order to get the drag of the propeller, we remove the propeller and run the setup at different flow conditions. The load cell reading now gives the drag reading. The actual thrust is calculated by adding this drag component to the load cell reading.

Chart Title

y = -0.3749x

-250

-200

-150

-100

-50

00 100 200 300 400 500 600

vel square

dra

g

drag vs vel square Linear (drag vs vel square)

Graph 2: Drag Vs Velocity Square. 3.3 CT vs J comparison Here the thrust was calculated for different flow velocities for I.C. Engine set up and D.C.Motor Assembly separately. The results for the two were compared.

comparison

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.2 0.4 0.6 0.8 1 1.2

J

Ct

IC electric D.C. motor

Graph 3: Thrust characteristics comparison of DC motor and IC engine

3.4 SFC vs RPM In this experiment SFC was measured at different RPM. The weight of fuel consumed was measured for every 1 minute. The fuel consumption for 10 minutes was taken for average.

rpm vs sfc

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 2000 4000 6000 8000 10000 12000

RPM

SFC

(gm

/W.h

r)

Graph 4: RPM vs SFC

3.5 TSFC vs RPM TSFC stands for Thrust Specific Fuel Consumption. In this experiment TSFC at different RPM was measured and observed that TSFC decreases with increase in RPM.

rpm vs tsfc

0.00E+00

2.00E-06

4.00E-06

6.00E-06

8.00E-06

1.00E-05

1.20E-05

1.40E-05

1.60E-05

0 2000 4000 6000 8000 10000 12000

RPM

TSFC

(kg

/N.s

)

Graph 5:Rpm Vs TSFC

References:

1. Anderson, J.D. Anderson, Introduction to Flight, Tata Mc Graw Hills Company, 1984.

2. Micro/Mini Aerial Vehicle Propulsion System Studies, Kailash Kotwani, Nishikant Prabhu, Yogesh Bhumkar, Centre for Aerospace System & Design Engg. (CASDE) Department, Department of Aerospace Engineering IIT Bombay.

3. Jason Gaza, Kortny Hall, Ed Marks Propellor Characteristics, Deptt. of Aerospace and Mechanical Engg., University of Notre Dame, April 23,2001.

4. Joel M. Grasmeyer and Matthew T. Keennon, Development of Black Widow Micro Aerial Vehicle, AIAA 2001-0127.

Acknowledgement

We would like to express our heartfelt gratitude to Prof. S.K.Sane for his help & guidance throughout the project work. We would also like to thank Kailash Kotwani and Arvind for their immense support and guidance during the course of the project. We would also like to thank our colleagues Nikhil, Sanketh for helping us all along.